Understanding Upper Brachial Plexus Palsies

By Dr. Oren Michaeli, DO – Board Certified General Surgeon, Fellowship-Trained in Hand Surgery, Microsurgery, and Peripheral Nerve Surgery

Introduction

Layman’s Explanation:
The brachial plexus is a group of nerves in your neck and shoulder that control arm movement and sensation. An upper brachial plexus palsy—often involving the C5 and C6 nerve roots—happens when these nerves are stretched or torn, typically due to a force that bends the neck away from the shoulder. Common scenarios include motorcycle, bicycle accidents, sports accidents or even a fall where the shoulder is pushed downward and the head/neck is pulled upward, stretching the nerves.

Upper Brachial Plexus Injury Mechanism

Muscles/Common Functions Affected:

• Difficulty lifting the arm away from the body (deltoid/supraspinatus weakness)

• Trouble bending the elbow (biceps, brachialis)

• Difficulty rotating the arm outward (infraspinatus)

This is a dermatome or a map of where one would expect to experience numbness if the corresponding nerve is avulsed or severely damaged. For upper plexus injuries pay attention to the areas in yellow and purple.

• Sensation Lost:

  • Skin over the outer (lateral) part of the shoulder and down the arm.

  • Possible numbness around the thumb-side of the forearm and hand.

More Technical Insight:

• Mechanism: Typically involves traction on the upper trunk (C5-C6, sometimes C7).

• Muscles Involved: Deltoid, biceps brachii, brachialis, brachioradialis, and infraspinatus.

• Sensory Deficit: Lateral upper limb (C5-C6 dermatomes), including parts of the thumb and index radial side.

• Surgery Timing: If no signs of spontaneous recovery or reinnervation by 3 months, surgical exploration (neurolysis, nerve grafts/transfers) is recommended to optimize functional outcomes.

Treatment Options

1. Surgical Exploration & Neurolysis

   • Layman’s Terms: The surgeon checks the damaged nerves and carefully frees them from any scar tissue.

   • Technical Insight: Neurolysis can restore conduction if nerves are intact but encased in fibrotic tissue.

2. Nerve Transfers

   • Layman’s Terms: Borrowing healthy nerves from nearby muscles to “rewire” the injured area. This will discussion should be focused on functions lost and functions we would like to gain. In this situation one can think that we “borrow from Peter to pay Paul”. We sacrifice a less critical function or muscle group to power one that is more critical.

   • Technical Insight: Common transfers for an upper plexus palsy would be the spinal accessory nerve (CN11) to the supra scapular nerve (C5,C6), and nerve to the long head of the tricep (C5, C6, C7, C8, T1)to the anterior division of the axillary nerve (C5,C6) to improve shoulder function. To restore elbow flexion we transfer fascicles from the median (C6,C7,C8,T1) and the ulnar nerve (C8-T1) to the musculocutaneous nerve (C5,C6,C7).

   • Summary: Nerves that are missing are C5, C6, +/-C7, Nerves present +/-C7, C8, T1

     • SAN —> SSN: CN11 replaces part of C5,C6

     • Tricep —> auxiliary: C7, C8, T1 replaces C5,C6

     • Median —> MCN: C8, T1 replaces C5,C6

     • Ulnar —> MCN: C8, T1 replaces C5,C6

3. Adjunct Therapies

   • Intraoperative Nerve Stimulation: Ensures the right donor nerves are selected.

   • Nerve Wrapping: Reduces future scarring.

   • Adipose-Derived Stem Cells (Experimental): May help boost nerve healing.

Consultation and Next Steps

If you suspect an upper plexus injury and have not seen meaningful recovery by 3 months, call Dr. Oren Michaeli at (212) 540-4263 or visit Hand Nerve Microsurgery.

• Remote or International? We can arrange video consultations and collaborate with a local occupational therapist to evaluate your condition and review medical records.

• Insurance & Travel: We frequently work with out-of-network plans to minimize your costs. Depending on your policy, travel and lodging may also be covered.